<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>
  <script>
    //load事件 响应数据可用时触发 IE6~8不支持
    //error事件 请求错误时触发 IE10支持
    //abort事件 终止请求触发
    //timeout事件 请求超时时触发
    const url = 'https://www.imooc.com/api/http/search/suggest?words=js';
    const xhr = new XMLHttpRequest
    xhr.onload = () => {
      if (xhr.readyState !== 4) return;
      if ((xhr.status >= 200 && xhr.status < 300) || xhr.status === 304) {
        console.log(xhr.responseText);
        console.log(typeof xhr.responseText);
      }
    }
    xhr.open('GET', url, true)
    xhr.send(null)
  </script>
</body>
</html>